// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Creates a unified stream based on the cras (ChromeOS audio server) interface.
//
// CrasUnifiedStream object is *not* thread-safe and should only be used
// from the audio thread.

#ifndef MEDIA_AUDIO_CRAS_CRAS_UNIFIED_H_
#define MEDIA_AUDIO_CRAS_CRAS_UNIFIED_H_

#include <cras_client.h>
#include <stddef.h>
#include <stdint.h>

#include <memory>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/time/time.h"
#include "media/audio/audio_io.h"
#include "media/base/audio_parameters.h"

namespace media {

class AudioManagerCras;

// Implementation of AudioOuputStream for Chrome OS using the Chrome OS audio
// server.
// TODO(dgreid): This class is used for only output, either remove all the
// relevant input code and change the class to CrasOutputStream or merge
// cras_input.cc into this unified implementation.
class MEDIA_EXPORT CrasUnifiedStream : public AudioOutputStream {
public:
    // The ctor takes all the usual parameters, plus |manager| which is the
    // audio manager who is creating this object.
    CrasUnifiedStream(const AudioParameters& params, AudioManagerCras* manager);

    // The dtor is typically called by the AudioManager only and it is usually
    // triggered by calling AudioUnifiedStream::Close().
    ~CrasUnifiedStream() override;

    // Implementation of AudioOutputStream.
    bool Open() override;
    void Close() override;
    void Start(AudioSourceCallback* callback) override;
    void Stop() override;
    void SetVolume(double volume) override;
    void GetVolume(double* volume) override;

private:
    // Handles captured audio and fills the ouput with audio to be played.
    static int UnifiedCallback(cras_client* client,
        cras_stream_id_t stream_id,
        uint8_t* input_samples,
        uint8_t* output_samples,
        unsigned int frames,
        const timespec* input_ts,
        const timespec* output_ts,
        void* arg);

    // Handles notification that there was an error with the playback stream.
    static int StreamError(cras_client* client,
        cras_stream_id_t stream_id,
        int err,
        void* arg);

    // Chooses the correct audio callback based on stream direction.
    uint32_t DispatchCallback(size_t frames,
        uint8_t* input_samples,
        uint8_t* output_samples,
        const timespec* input_ts,
        const timespec* output_ts);

    // Writes audio for a playback stream.
    uint32_t WriteAudio(size_t frames,
        uint8_t* buffer,
        const timespec* sample_ts);

    // Deals with an error that occured in the stream.  Called from StreamError().
    void NotifyStreamError(int err);

    // The client used to communicate with the audio server.
    cras_client* client_;

    // ID of the playing stream.
    cras_stream_id_t stream_id_;

    // PCM parameters for the stream.
    AudioParameters params_;

    // Size of frame in bytes.
    uint32_t bytes_per_frame_;

    // True if stream is playing.
    bool is_playing_;

    // Volume level from 0.0 to 1.0.
    float volume_;

    // Audio manager that created us.  Used to report that we've been closed.
    AudioManagerCras* manager_;

    // Callback to get audio samples.
    AudioSourceCallback* source_callback_;

    // Container for exchanging data with AudioSourceCallback::OnMoreData().
    std::unique_ptr<AudioBus> output_bus_;

    // Direciton of the stream.
    CRAS_STREAM_DIRECTION stream_direction_;

    DISALLOW_COPY_AND_ASSIGN(CrasUnifiedStream);
};

} // namespace media

#endif // MEDIA_AUDIO_CRAS_CRAS_UNIFIED_H_
